In the field of IVD, multi-chamber plates have become a widely used tool. Thus, various geometries for chamber plates and methods for filling them are known. Multi-chamber plates may comprise a matrix of wells, for example thousands of micro wells or nano wells, defining the chambers. Reading out such small structures on multi-chamber plates is challenging.
Several methods exist for reading out small structures, for example warps, bends in surfaces of labels, cards or other data storage media. For example, U.S. Pat. No. 4,745,484 A describes a method and apparatus for reading data in a data field on a data surface of a storage medium in which the data surface may be nonplanar and depth wise regions of the data field are brought one-by-one into the region of focus of a CCD area array. A set of partial images is formed which are then merged together into a composite image of the data field to be read. The storage medium is disposed on a vacuum chuck. Imaging optics, such as a single lens, zoom lens or lenticular array images regions of the data surface which are within a region of focusing onto the CCD area array. A piezoelectric device or a linear variable differential transformer serve as a Z-axis focusing element which responds to oscillator or electrical control signals to change the relative distance between the CCD area array and a reference plane of the data surface. The partial images formed are either merged in semiconductor memory by a processor or are merged automatically by the CCD area array.
In such methods, data spots are stored at uneven depth over the surface of the medium and relative to a focal plane of the optical detection system of a reader. A major case of this unevenness is that the data surface has tilts, warps or bends relative to an ideal or “target” surface parallel to the focal plane. An ensuing problem is that some data spots are out of the target plane resulting in errors in reading the data. Various auto-focus mechanisms, usually servo-controlled, are known, which control a position of a lens to bring the data spot into sharp focus of a detector. For example, EP 0 216 923 B1 describes a method of inspecting a surface illuminated with light comprising the steps of: illuminating the surface with light, imaging light from said surface reflected from a screen or other member and re-reflected from said surface to form an image of said surface on an image sensor, and determining from said image detected or recorded by said image sensor, the condition of said surface.
U.S. Pat. No. 4,963,724 A describes an apparatus for producing an optical image contrast which may be used in a microscope. Specifically, the apparatus is based on the Moiré effect and uses two screens or gratings which are rotated simultaneously at different angular velocities in order to increase the depth of focus and resolution achievable with conventional systems.
DE 3 527 074 A1 describes an arrangement for determining the surface contour of objects by means of the moiré technique and is intended, in particular, for use in stereomicroscopes, particularly in surgical microscopes, or else in similar systems for inspection. The aim is for the moiré fringes that are generated for determining the surface contour to be displaced in a measurable fashion without changing the position of the object, and in addition it is to be possible for the vertical resolution to be improved. A surgical microscope with an assigned projection system for a grid and with a projection or reference grid that is located in the observation beam path of the surgical microscope and in the beam path of the projection system and is intended for producing a morié pattern has a tiltable, plane-parallel glass plate arranged downstream of the projection grid in the projection beam path, as a result of which the relative position of grid and reference grid is altered and the morié pattern or contour lines are measurably displaced. The observability can be substantially increased by periodic tilting of the plane-parallel plate, and the number of contour lines can be increased by pulsed operation of the illuminating device of the projection system and periodic tilting, synchronized with the light pulses, of the plane-parallel plate, and the contour lines can be displaced in a pinpointed fashion.
The methods for reading out small structures, however, exhibit some significant disadvantages and shortcomings. Thus, such methods are complicated. Furthermore, such methods are not suitable for multi-chamber plates. For example such methods require fiducials which need space which cannot be used for samples. Autofocus techniques, however, may lead to the necessity that each field of view needs to be captured several times, each with different foci, in order to determine enough wells sharply to assign individual coordinates. At readout of thousands of micro wells or nano wells, it must be ensured that each individual well is counted and none of them double. This is, however, challenging if the field of view of an optical system cannot cover the multi-chamber plate such that the optical system images only partial images of the multi-chamber plate. In this case stitching of fields of view, in particular of the partial images, is necessary and columns and/or rows need to be counted in order to know the exact displacement during stitching of partial images. Furthermore, in contrast to data storage media like cards etc. the multi-chamber plate may be bent and warped during thermal cycling.
It is therefore an objective of the present disclosure to provide a multi-chamber plate analysis device and a method for analyzing a multi-chamber plate, which at least partially overcome the shortcomings of devices and methods known from prior art. Specifically, devices and methods for simple and reliable readout of multi-chamber plates should be provided.